Temperature and Absolute Zero
When an object feels hot, the atoms inside it are moving fast in random
directions, and when it feels cold, they are moving slowly. Our body
interprets that random atomic motion into what we feel as hot and cold, and a
thermometer interprets that atomic motion as a certain number of degrees.
So when I'm heating something, I'm just making its atoms move faster?
Exactly. If the object is a solid the atoms are vibrating back and forth, and
if it is a gas like the air, the atoms are flying around much like little
They are bouncing around so that sometimes an atom is going fast, and other
times it is slow. It seems like its temperature must be changing all the
In a group of atoms there is always a whole range of speeds, but while the
speed of one atom changes, the average of all of them does not. See how each
time an atom slows down, there has to be another that speeds up? So
temperature is really describing the range of speeds of the bunch of atoms
together. Physicists often like to use a different scale for temperature that
is directly related to the speed atoms are going in a gas. This is called the
Absolute scale, and one degree on it is the same as one degree centigrade,
which is 9/5 of a degree Fahrenheit. The difference between the Centigrade and
Absolute scales is the zero label.
So that is as cold as the atoms can be. We call that Absolute Zero.
I get it! When the atoms are all stopped the gas is ABSOLUTELY as cold as can
Yes, and that is really cold. The thermometer shows a comparison of the
Absolute (also known as the Kelvin) and Fahrenheit scales of temperature.
Absolute Zero is -459 degrees Fahrenheit.